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Little attention has been given to optimizing statistical power for monitoring stream fish assemblages. We explored the relationship between temporal variability and statistical power using 34 metrics from fish community data collected annually at six sites over 10 years via electrofishing. Metric variability differed by the life stage and group of species considered, use of abundance or mass data, and data standardization technique. Lower variability was associated with community data, abundance data, and time-based standardizations, while greater variability was associated with young-of-the-year data, mass data, and area-based standardizations. Simulation-based power analysis indicated metric choice, and to a lesser degree, monitoring design (annual, biennial, endpoints, or haphazard sampling) influenced power to detect change. Across a fixed number of surveys (N = 60), endpoints sampling performed best. The N needed to detect change was heavily dependent upon metric choice for all monitoring designs, with the most biologically specific metrics requiring greater N. Large savings in effort and resource expenditure can be obtained utilizing biologically relevant metrics that are robust to temporal noise within an appropriate sampling design. L'optimisation de l'efficacite statistique pour la surveillance des assemblages de poissons de cours d'eau a recu peu d'attention. Nous explorons le lien entre la variabilite temporelle et l'efficacite statistique en utilisant 34 parametres tires de donnees sur des communautes de poissons recueillies annuellement dans six sites, sur une periode de 10 ans, par peche electrique. La variabilite des parametres differe selon l'etape du cycle biologique et le groupe d'especes examines et le type de donnees (abondance ou masse) et la methode de normalisation des donnees utilises. Une plus faible variabilite est associee aux donnees sur les communautes, aux donnees sur l'abondance et aux normalisations basees sur le temps, alors qu'une plus grande variabilite est associee aux donnees sur les jeunes de l'annee, aux donnees sur la masse et aux normalisations basees sur la superficie. L'analyse de l'efficacite basee sur la simulation indique que le choix des parametres et, dans une moindre mesure, le schema de surveillance (annuel, bisannuel, indicateurs d'effet ou echantillonnage a l'aveuglette) influencent l'efficacite de la detection de changements. Pour un nombre fixe de releves (N = 60), l'echantillonnage d'indicateurs d'effet donne les meilleurs resultats. Le N necessaire pour detecter des changements depend fortement du choix des parametres pour tous les schemas de surveillance, les parametres les plus specifiques sur le plan biologique necessitant des N plus grands. D'importantes reductions de l'effort et des ressources depensees peuvent etre obtenues en utilisant des parametres pertinents du point de vue biologique sur lesquels le bruit temporel a peu d'influence, dans un schema d'echantillonnage approprie. [Traduit par la Redaction], Introduction A great deal of time and resources have been devoted to environmental monitoring over the past few decades, yet notably less effort has been devoted to understanding the ability [...]

Surface waters across much of New York's Adirondack Mountains were acidified in the late 20th century but began to recover following the 1990 amendments to the Clean Air Act. Little data, however, are available to characterize biological impacts and predict recovery of fish assemblages in streams of the region. Quantitative fish and chemistry surveys were completed in 47 headwater streams during summer 2014-2016 to develop logistic (probabilistic) models that characterize the status of contemporary fish assemblages and predict how different nitrogen (N) and sulfur (S) deposition loads may affect future fish assemblages. Models for inorganic monomeric aluminum ([Al.sub.i]) and richness [greater than or equal to] 1 species and for acid neutralizing capacity (ANC) and total density >400 fish/0.1 ha, total biomass >1500 g/0.1 ha, brook trout (Salvelinus fontinalis) density >0 or >200 fish/0.1 ha, and brook trout biomass >1000 g/0.1 ha were suitable for evaluating community and population responses to changes in acid-base chemistry. Anticipated changes in national (US) secondary standards for atmospheric emissions of nitrogen oxides (N[O.sub.x]) and sulfur oxides (S[O.sub.x]) to achieve target N and S deposition loads will alter acid-base chemistry and the probabilities for observing various levels of fish metrics in streams across the region and elsewhere. Les eaux de surface dans une bonne partie des monts Adirondack de l'Etat de New York se sont acidifiees vers la fin du 20e siecle, mais ont commence a se retablir dans la foulee des amendements de 1990 a la Clean Air Act. Peu de donnees etaient toutefois disponibles pour caracteriser les impacts biologiques et predire le retablissement des assemblages de poissons dans les cours d'eau de la region. Des recensements quantitatifs de poissons et des leves chimiques ont ete realises dans 47 cours d'eau d'amont durant les etes de 2014 a 2016, afin d'elaborer des modeles logistiques (probabilistes) qui caracterisent l'etat des assemblages de poissons actuels et de predire l'incidence possible de differentes charges de depot d'azote (N) et de soufre (S) sur les assemblages de poissons futurs. Des modeles pour l'aluminium inorganique monomere (Ali) et une richesse [greater than or equal to] 1 espece, ainsi que pour le potentiel de neutralisation de l'acide (PNA) et une densite totale >400 poissons/0,1 ha, une biomasse totale >1500 g/0,1 ha, une densite d'ombles de fontaine (Salvelinus fontinalis) >0 ou >200 poissons/0,1 ha, et une biomasse d'ombles de fontaine >1000 g/0,1 ha se pretent a l'evaluation des reactions des communautes et des populations a des changements des conditions acidobasiques. Des modifications prevues a des normes secondaires nationales (Etats-Unis) concernant les emissions atmospheriques d'oxydes d'azote (N[O.sub.x]) et d'oxydes de soufre (S[O.sub.x]) pour atteindre des cibles de charges de depot de N et S modifieront les conditions acidobasiques et les probabilites d'observer des valeurs variees de parametres associes aux poissons dans les cours de la region et ailleurs. [Traduit par la Redaction], Introduction Although acid deposition has declined precipitously across eastern North America (McHale et al. 2017), subsequent improvements in water chemistry and biology of streams appear to be lagging considerably (Baldigo [...]

Context: Preservation of genetic diversity is a commonly cited, yet under-evaluated aspect of species conservation plans. Understanding the influence of human-mediated translocations and habitat constraints on landscape patterns of genetic structure in threatened fish species is essential to maintaining biodiversity and adaptive potential. Objectives: We evaluated the degree of influence from supplemental stocking, assessed the spatial population genetic structure, and examined the potential relationship between hybridization and ecology for Brook Trout (Salvelinus fontinalis) in the Black River watershed in New York State, USA. Methods: We used 13 microsatellite loci from over 450 fish at 18 sampling locations to map genetic structure and diversity, estimate the level of influence from stocked conspecifics, and model the relationship between hybridization and ecological characteristics. Results: We found widespread genetic introgression attributable to state-based stocking activities and a pattern of hierarchical genetic diversity across the landscape, which has additionally been influenced by geography. Site-specific fish assemblage variables appear to be unrelated to introgressive hybridization from stocked conspecifics, and only one hydrochemical variable, SO42−, exhibited strong explanatory power in predicting hybridization between wild and supplemented fish. A single locality exhibited genetic structure consistent with no history of introgression potentially associated with differences in elevation, and thus contributed disproportionately to the level of genetic diversity observed across the landscape. Conclusions: When examining genetic structure in fluvial riverine networks, it is important to consider the combined and interacting effects of both hybridization and habitat, which may result in augmented genetic structure not predictable from any single factor. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) analysis is rapidly evolving as a tool for monitoring the distributions of aquatic species. Detection of species’ populations in streams may be challenging because the persistence time for intact DNA fragments is unknown and because eDNA is diluted and dispersed by dynamic hydrological processes. During 2015, the DNA of Brook TroutSalvelinus fontinaliswas analyzed from water samples collected at 40 streams across the Adirondack region of upstate New York, where Brook Trout populations were recently quantified. Study objectives were to evaluate different sampling methods and the ability of eDNA to accurately predict the presence and abundance of resident Brook Trout populations. Results from three-pass electrofishing surveys indicated that Brook Trout were absent from 10 sites and were present in low (<100 fish/0.1 ha), moderate (100–300 fish/0.1 ha), and high (>300 fish/0.1 ha) densities at 9, 11, and 10 sites, respectively. The eDNA results correctly predicted the presence and confirmed the absence of Brook Trout at 85.0–92.5% of the study sites; eDNA also explained 44% of the variability in Brook Trout population density and 24% of the variability in biomass. These findings indicate that eDNA surveys will enable researchers to effectively characterize the presence and abundance of Brook Trout and other species’ populations in headwater streams across the Adirondack region and elsewhere. Received April 15, 2016; accepted September 26, 2016 Published online December 6, 2016 [ABSTRACT FROM AUTHOR]

Water temperature is a key component of aquatic ecosystems because it plays a pivotal role in determining the suitability of stream and river habitat to most freshwater fish species. Continuous temperature loggers and airborne thermal infrared (TIR) remote sensing were used to assess temporal and spatial temperature patterns on the Upper Schoharie Creek and West Kill in the Catskill Mountains, New York, USA. Specific objectives were to characterize (1) contemporary thermal conditions, (2) temporal and spatial variations in stressful water temperatures, and (3) the availability of thermal refuges. In-stream loggers collected data from October 2010 to October 2012 and showed summer water temperatures exceeded the 1-day and 7-day thermal tolerance limits for trout survival at five of the seven study sites during both summers. Results of the 7 August 2012 TIR indicated there was little thermal refuge at the time of the flight. About 690,170 m2of water surface area were mapped on the Upper Schoharie, yet only 0.009% (59 m2) was more than 1.0 °C below the median water surface temperature (BMT) at the thalweg and no areas were more than 2.0 °C BMT. On the West Kill, 79,098 m2were mapped and 0.085% (67 m2) and 0.018% (14 m2) were BMT by 1 and 2 °C, respectively. These results indicate that summer temperatures in the majority of the study area are stressful for trout and may adversely affect growth and survival. Validation studies are needed to confirm the expectation that resident trout are in poor condition or absent from the downstream portion of the study area during warm-water periods. [ABSTRACT FROM AUTHOR]